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Long-chain omega-3 fatty acids—eicosapentaenoic and docosahexaenoic acids—are essential components of human diets and some aqua and animal feeds, but they are sourced from finite marine fisheries, and are in short supply and deficient in large parts of the world. We use quantitative systems analysis to model the current global eicosapentaenoic acid/docosahexaenoic acid cycle and identify options for increasing supply. Opportunities lie in increased by-product utilization and food waste prevention. However, economic, resource, cultural and technical challenges need to be overcome. Omega-3 fatty acids are important for the human diet and for some aqua and animal feeds. This study reports a supply gap, and using quantitative systems analysis identifies targets for increasing efficiency in the global omega-3 cycle.

Global markets and supply chains for the long-chain omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are complex. EPA and DHA are crucial materials for fortified foods, nutraceutical and pharmaceutical markets. They also provide essential nutrition in animal feeds, notably to the growing aquaculture industry, currently the major market (by volume). Traditional supply routes through fish oil and fishmeal are recognized as being finite, but novel sources such as algal oils and genetically modified (GM) seed oil crops (e.g., canola, camelina) and yeasts are now commercial products or very close to commercialization.

Efficiency assessments of marine ingredient use in aquaculture are required to fully understand their contribution to global seafood supply and their impacts on all UN Sustainable Development Goals. Fish In: Fish Out (FIFO) ratios have become the principal metric used to ensure aquaculture does not negatively impact wild fish stocks. However, several approaches have been advocated to calculate the FIFO ratio and there have been criticisms that the different approaches employed lead to over- or under- estimates of the dependence of aquaculture on marine ingredients. Critically, FIFO does not align with Life Cycle Assessment as a measure of other environmental impacts. In this paper we present an alternative method to calculate the FIFO ratio based on the principle of economic allocation (economic Fish In: Fish Out – eFIFO) as commonly used in Life Cycle Assessments. Economic allocation acts as a proxy for the nutritional value of ingredients and places higher importance on the more limiting co-products generated and their relative demand. Substitution of marine ingredients by alternate feed ingredients has significantly reduced the amount of fishmeal and fish oil in aquafeed formulations for most farmed fish species, resulting in a continually decreasing FIFO ratio. Resultsshow that most aquaculture species groups assessed in this study are net producers of fish, while salmon and trout aquaculture are net neutral, producing as much fish biomass as is consumed. Overall, global fedaquaculture currently produces three to four times as much fish as it consumes. Tracking historical prices offish oil against fishmeal, the relative higher price of fish oil leads to relatively higher allocation of fish to fish oil compared to fishmeal. This leads to relatively higher eFIFO for species with high fish oil requirements.

Aquaculture is currently the fastest expanding global animal food production sector and is a key future contributor to food security. An increase in food security will be dependent upon the development and improvement of sustainable practices. A prioritization exercise was undertaken, focusing on the future knowledge needs to underpin UK sustainable aquaculture (both domestic and imported products) using a ‘task force’ group of 36 ‘practitioners’ and 12 ‘research scientists’ who have an active interest in sustainable aquaculture. A long list of 264 knowledge needs related to sustainable aquaculture was developed in conjunction with the task force. The long list was further refined through a three stage process of voting and scoring, including discussions of each knowledge need. The top 25 knowledge needs are presented, as scored separately by ‘practitioners’ or ‘research scientists’. There was similar agreement in priorities identified by these two groups. The priority knowledge needs will provide guidance to structure ongoing work to make science accessible to practitioners and help to prioritize future science policy needs and funding. The process of knowledge exchange, and the mechanisms by which this can be achieved, effectively emerged as the top priority for sustainable aquaculture. Viable alternatives to wild fish-based aquaculture feeds, resource constraints that will potentially limit expansion of aquaculture, sustainable offshore aquaculture and the treatment of sea lice also emerged as strong priorities. Although the exercise was focused on UK needs for sustainable aquaculture, many of the emergent issues are considered to have global application.

Fisheries and aquaculture production, imports, exports and equitability of distribution determine the supply of aquatic food to people. Aquatic food security is achieved when a food supply is sufficient, safe, sustainable, shockproof and sound: sufficient, to meet needs and preferences of people; safe, to provide nutritional benefit while posing minimal health risks; sustainable, to provide food now and for future generations; shock-proof, to provide resilience to shocks in production systems and supply chains; and sound, to meet legal and ethical standards for welfare of animals, people and environment. Here, we present an integrated assessment of these elements of the aquatic food system in the United Kingdom, a system linked to dynamic global networks of producers, processors and markets. Our assessment addresses sufficiency of supply from aquaculture, fisheries and trade; safety of supply given biological, chemical and radiation hazards; social, economic and environmental sustainability of production systems and supply chains; system resilience to social, economic and environmental shocks; welfare of fish, people and environment; and the authenticity of food. Conventionally, these aspects of the food system are not assessed collectively, so information supporting our assessment is widely dispersed. Our assessment reveals trade-offs and challenges in the food system that are easily overlooked in sectoral analyses of fisheries, aquaculture, health, medicine, human and fish welfare, safety and environment. We highlight potential benefits of an integrated, systematic and ongoing process to assess security of the aquatic food system and to predict impacts of social, economic and environmental change on food supply and demand.

Commercial farming of Atlantic salmon in Scotland started in 1969 and has since expanded to produce > 179,000 t year − 1 . A government department has published annual statistics and information on the seawater and freshwater sub-sectors of the Scottish salmon farming industry since 1979, and this review collates and discusses metrics covering aspects of production, farm sites and systems, fish performance, socio-economics and environmental pressures. Trends illustrated in this case study of aquaculture development include: initial increases in numbers of farms and companies, followed by decreases due to industry consolidation; increases in average farm size, and productivity of systems and employees; increases in survival, size at age and productivity of fish (yield per smolt, ova per broodstock); reduced dependence on wild stocks for ova. This case study also illustrates the importance of disease management, control of biological processes to overcome natural seasonality (i.e. production of out-of-season smolt), and the international nature of aquaculture. Improvements in fish survival, growth and productivity are attributed to progress in vaccination and health management (including fallowing), husbandry, system design, feed formulation and provision, and introduction of technology and mechanisation. Salmon farming is discussed in relation to the challenging strategy of “sustainable intensification”. Improved growth and survival over a period of increasing rearing unit size, farm size and output and decreasing relative staff input counters the common assumption that intensification compromises animal welfare. The value of capturing time series data on industry wide metrics is illustrated as it enables identification of trends, underperformance and bench-marking, as well as assessment of resource use efficiency, environmental pressures, and ultimately sustainability. Statement of relevance This review is an original collation of a comprehensive set of time series of official statistics on an entire, discrete and regionally important sector of commercial aquaculture.